Canis ISSN: 2398-2942

Craniectomy/Craniotomy

Synonym(s): intracranial, extracranial skull fracture

Contributor(s): Rodney Bagley, Prof Mark Rochat

Introduction

  • A craniotomy is removal of a portion of the skull for access to the intracranial space, with subsequent replacement of bone.
  • A craniectomy is removal of a portion of the skull for access to the intracranial space, without subsequent replacement of bone.
  • Penetrating wounds to the brain from a skull fracture may result in mechanical disruption of intracranial tissues (primary injury).
  • This primary injury may initiate a number of secondary pathophysiological sequelae such as:
    • Metabolic alterations in neuronal or glial cells.
    • Impairment of vascular supply to normal tissue (ischemia).
    • Impairment of cerebrovascular autoregulation.
    • Hemorrhage (intraparenchymal, intraventricular, extradural or subdural).
    • Irritation (seizure generation).
    • Obstruction of the ventricular system.
    • Edema formation.
    • Production of physiologically active products.
    • Increased intracranial pressure (ICP).
  • A major tenet of the Monroe-Kellie doctrine is that intracranial contents are confined within the cranium.
  • It would follow, therefore, that surgical removal of this structure would potentially relieve ICP elevations.
  • Craniectomy and durotomy has been shown to lower ICP by 15 and 65 %, respectively, in dogs, cats and humans.
  • Intracranial pressures in normal dogs approached atmospheric pressure when a lateral rostrotentorial craniectomy and durotomy is performed.
  • Craniectomy can also be used to remove tumors or other growths from the skull and adjacent soft tissues.
  • Craniotomy, while more technically demanding, may be indicated for extensive approaches that leave large areas of brain exposed or in animals that have little soft tissue coverage of exposed brain, typically brachycephalic breeds of dogs.

Uses

Extracranial
  • Reduction of fractures which involve the orbit and threaten the eye.
  • Removal of tumors or tumor-like conditions that involve the skull or adjacent soft tissues.
Intracranial
  • Reduction of depressed fractures which impinge directly on brain.
  • Removal of tumors of the brain and meninges.
  • Removal of other intracranial masses.
  • Biopsy of intracranial masses Biopsy: brain.

Advantages

  • Provides immediate direct decompression of brain if intracranial pressure increased.
  • Provides access for biopsy and/or removal of intracranial masses.
  • Allows for continued reduction of intracranial pressure after surgery.
  • Craniotomy affords protection of the brain after surgery.

Disadvantages

  • Requires relatively experienced surgeon to prevent further damage to the brain.
  • Requires relatively experienced anesthetic management during surgery.
  • Requires relatively experienced management after surgery.
  • Requires some specialized equipment.
  • Craniectomy may expose the brain to excessive risk of injury after surgery, especially with extensive resection and in dogs with little or no muscle coverage of the exposed brain.
  • Craniotomy does not allow for continued reduction in intracranial pressure after surgery.
  • Wires used to secure the craniotomy may interfere with imaging studies; titanium plates and screws or monofilament suture may be better choices for cases where subsequent imaging studies are considered.

Requirements

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Preparation

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Procedure

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Aftercare

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Outcomes

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Prognosis

  • Good.
  • Ultimate functional recovery remains dependent upon the underlying primary brain damage inflicted by the disease process.
  • In general, lesions of supratentorial structures or the cerebellum have a better overall prognosis for recovery than lesions involving the brain stem.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Gordon P N, Kornegay J N, Lattimer J C et al (2005) Use of a rivet-like titanium clamp closure system to replace an external frontal bone flap after transfrontal craniotomy in a dog. JAVMA 226 (5), 752-755 PubMed.
  • Bagley R S (1996) Pathophysiologic sequelae of intracranial disease. Vet Clin North Am 26 (4), 711-733 PubMed.
  • van Loon J, Shivalkar B, Plets C et al (1993) Catecholamine response to a gradual increase of intracranial pressure. J Neurosurg 79 (5), 705-709 PubMed.
  • Bouma G J, Muizelaar J P, Bandoh K et al (1992) Blood pressure and intracranial pressure-volume dynamics in severe head injury: relationship with cerebral blood flow. J Neurosurg 77 (1), 15-19 PubMed.
  • Sorjonen D C, Thomas W B, Myers L J et al (1991) Radical cerebral cortical resection in dogs. Prog Vet Neurol (4), 225-36 VetMedResource.
  • Lyons M K & Meyer F B (1990) Cerebrospinal fluid physiology and the management of increased intracranial pressure. Mayo Clinic Proc 65 (5), 684-707 PubMed.
  • Germon K (1988) Interpretation of ICP pulse waves to determine intracerebral compliance. J Neurosci Nurs 20 (6), 344-351 PubMed.
  • Lobato R D, Sarabia R, Cordobes F et al (1988) Post-traumatic cerebral hemispheric swelling. Analysis of 55 cases studied with computerized tomography.​ J Neurosurg 68 (3), 417-423 PubMed.
  • Orbrist W D, Langfitt T W, Jaggi J L et al (1984) Cerebral blood flow and metabolism in comatose patients with acute head injury. Relationship to intracranial hypertension.​ J Neurosurg 61 (3), 241-253 PubMed.
  • Kornegay J N, Oliver J E & Gorgacz E J (1983) Clinicopathologic features of brain herniation in animals. JAVMA 182 (10), 1111-1116 PubMed.
  • Nishio S, Ohta M, Abe M et al (1983) Microvascular abnormalities in ethylnitrosourea (ENU)-induced rat brain tumors - Structural basis for altered blood-brain-barrier function. Acta Neuropathol (Berl) 59 (1), 1-10 PubMed.
  • Tornheim P A, Liwnicz B H, Hirsch C S et al (1983) Acute responses to blunt head trauma. J Neurosurg 59 (3), 431-438 PubMed.
  • King J M, Roth L & Haschek W M (1982) Myocardial necrosis secondary to neural lesions in domestic animals. JAVMA 180 (2), 144-148 PubMed.
  • Enevoldsen E M & Jensen F T (1979) Autoregulation and CO2 responses of cerebral blood flow in patients with acute severe head injury. J Neurosurg 48 (5), 689-703 PubMed.
  • Reulen H J (1976) Vasogenic brain edema - New aspects in its formation, resolution and therapy. Br J Anaesth 48 (8), 741-752 PubMed.
  • Tornheim P A, McLaurin R L & Thorpe J F (1976) The edema of cerebral contusion. Surg Neurol (3), 171-175 PubMed.
  • Shapiro H M (1975) Intracranial hypertension. Therapeutic and anesthetic considerations. Anesthesiology 43 (4), 445-471 PubMed.

Other sources of information

  • Bagley R S (2003)Surgical approaches to the central nervous system - brain.In:Textbook of Small Animal Surgery.3rd edn. Slatter D (ed). Saunders W B, Philadelphia. pp 1163-1174.
  • Bagley R S (2003)Intracranial Surgery.In:Textbook of Small Animal Surgery.3rd edn. Slatter D (ed). Saunders W B, Philadelphia. pp 1261-1276.
  • Guyton A C (1986)Arterial pressure regulation:I. Rapid pressure control.In:Textbook of Medical Physiology.7th edn. Saunders W B, Philadelphia. pp 250-251.


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